How to Mitigate CVE-2025-29977 - Microsoft Excel Remote Code Execution Vulnerability

Spirity Security Advisor
2 days ago
2 min read

CVE-2025-29977 is a vulnerability in Microsoft Excel that allows an unauthorized attacker to execute code locally due to a use-after-free error. To protect your systems from this vulnerability, follow the steps outlined below.

1. Apply Security Updates

Ensure that you are running the latest version of Microsoft Excel and that all security updates have been applied. Microsoft regularly releases patches to address vulnerabilities. You can check for updates by:

Opening Excel and navigating to File > Account > Update Options.
Selecting Update Now to check for and install any available updates.

2. Disable Macros

Macros can be a vector for exploiting vulnerabilities. To minimize risk, disable macros in Excel unless absolutely necessary. You can do this by:

Going to File > Options > Trust Center > Trust Center Settings.
Selecting Macro Settings and choosing Disable all macros without notification.

3. Use Protected View

Enable Protected View for files originating from the internet or other untrusted sources. This feature opens documents in a read-only mode, reducing the risk of executing malicious code. To enable it:

Navigate to File > Options > Trust Center > Trust Center Settings.
Select Protected View and check all available options.

4. Educate Users

Conduct training sessions to inform users about the risks associated with opening unknown files or clicking on suspicious links. Encourage them to verify the source of any Excel files received via email or download.

5. Implement Endpoint Protection

Use endpoint protection solutions that include anti-malware and intrusion detection systems. These tools can help detect and prevent exploitation attempts related to vulnerabilities like CVE-2025-29977.

6. Monitor and Audit

Regularly monitor and audit Excel usage within your organization. Look for unusual activity that may indicate exploitation attempts, and respond accordingly.

7. Reference Official Documentation

Stay informed about updates and additional mitigation strategies by regularly checking the official Microsoft Security Response Center page for CVE-2025-29977: Microsoft Security Response Center.

By following these mitigation strategies, you can significantly reduce the risk associated with CVE-2025-29977 and enhance the security of your Microsoft Excel environment.